Development of high efficiency GaN-based multiquantum-well light-emitting diodes and their applications

Highly efficient GaInN-GaN multiple quantum-well (MQW) light-emitting diodes (LEDs) were successfully developed by the low-temperature AlN buffer layer method for metal-organic vapor phase epitaxy (MOVPE). The light-emitting layer of the GaInN-GaN MQW drastically enhances the performance of GaN-based LEDs in terms of the efficiency and spectrums. Flip-chip (FC) type MQW LEDs have been newly developed to increase efficiency in extracting light from the GaN-based crystal to the outside. The luminous intensities of FC type blue and green LEDs are typically 6 and 14 cd, respectively, at 20 mA. The output power of the FC-type LEDs was 14 mW at 20 mA, which was approximately two times higher than that of the conventional face-up type blue LEDs. The external quantum efficiency of blue FC-type LEDs was as high as 20% at 20 mA. New multicolor package was developed using these high performance nitride-based LEDs and commercial AlGaInP-based red LEDs, the color range of which is the largest among other flat panel display devices.